British species of Psyllida;. 551 



nerves pale greenish or yelloAvisli ; dorsal margin with 

 four small black grannies in the spaces enclosed by the 

 nerves. Legs pale green. 



Abdomen green. 



Length 1 \ line. 



This genus seems to unite Psylla with Trioza, but 

 differs from both in the shortness and fineness of the 

 antennas and the length of the face-lobes. Like Psylla it 

 has a costal stigma, but the elytra are shaped like those of 

 Trioza, from which genus it also difiers in having the 

 cubitus petiolate and the nervelets replaced by small 

 granules on the dorsal margin. Forster says there are 

 only three, but my specimens distinctly have four. 

 Bai'on de Fonscolombe, who gave to Forster the insects 

 from Avhich his description is made, says he believes he 

 obtained them from box {Pnx?is sempervirens^, and also 

 from other plants near Aix. Forster thi'ows doubt upon 

 the box theory, and perhaps correctly ; but if the insect 

 was found at Aix, I see no reason against its occurrence 

 here. 



The specimens which I possess were kindly presented 

 to me by M. Lethierry, and are from St. Girons (Ariege), 

 a department of France bordering on the Pyrenees. 



Genus Trioza, Forst. 



//e«rZ broader than long. Crotcn considerably deflected, 

 divided down the centre by a channel and with a fovea on 

 each side betAveen the eyes ; the space between the former 

 and the latter slightly raised ; anterior margin more or 

 less M-shaped; posterior margin more or less concave. 

 Ocelli placed as in Psylla. Face lobate ; lobes mode- 

 rately long, generally triangular in outline, acute at the 

 apex where the divergence is great. AntenncB 10-jointed, 

 formed as in Psylla, but shorter. 



Thorax : pronotum very narrow, collar-shaped, de- 

 flected ; sides with a depression causing the lateral margins 

 to become more or less lobate. Mesonotum and scutellum 

 as in Psylla. Elytra, generally transparent, lanceolate, 

 more or less acute at the apex ; costal margin convex, 

 without a stigma ; spaces enclosed by the nerves along 

 the dorsal margin Avith three nervelets ; upper branch of 

 the upper arm of the cubitus terminating almost in the 

 apex ; cubitus not petiolate. 



The lanceolate form of the elytra with the three nerve- 



